FIG. 1 is a prior art
A traditional LED lamp is shown in FIG. 1 where an LED chip 11 is mounted on a circuit board 10. When the LED chip 11 is energized, the bulb sheds light beams hemispherically or, nearly 180 degree in a section view. This hemispheric illumination lamp of FIG. 1 is not good to be used as a light source for a decorative lamp such as a ceiling lamp which is covered by a lampshade. A lampshade is a fixture that covers a light bulb on a lamp to diffuse the light beams it emits. A decorative lamp is usually configured with a lampshade that could be transparent or semi-transparent one and with a special outline design. In order to display the beauty of the lampshade, light beams should have to shed on most of the lampshade, an omnidirectional light source such as a traditional tungsten lamp is chosen to be used as the light source. The LED lamp as shown in FIG. 1 is not a good candidate to be used as the light source.
FIG. 2 is another prior art
A tungsten lamp is shown in FIG. 2 which is one of the traditional incandescent lamps. The tungsten lamp 12 has a full directional illumination capability, nearly 360 degree illumination in section view, which is a right choice to be used as a light source for a decorative lamp mentioned above. LED technology has been well developed in recent years. Data shows that LED lamps save 80% energy than incandescent lamps, 50% energy saving than fluorescent lamps. LED lamps have the advantages on energy saving and environmental protection, and have become a major trend of development in the lighting field. It is long desired if an omnidirectional LED lamp can be figured out to replace traditional incandescent lamps such as tungsten lamps with low energy efficient.